Firstly, Daily Mail are f*cking scum.
DP and I have decided to get married next year
However DP has said that we can’t get “officially” engaged (i.e. get a ring, announce to family and friends, start planning the wedding etc) until after his sister’s wedding at the beginning of October 
We are not close to SIL and stb-BIL (see them maybe 3-4 times a year and try to keep contact down as they are generally quite rude to us both and to other family members). We know they are likely to be annoyed and to make digs if we get engaged before their wedding because they generally can’t be happy for other people and because one of the first things they said to us after they got engaged last year was “nobody better steal our thunder on our wedding day!” At the time DP and I weren’t considering marriage so I just thought they sounded a bit unhinged to be worrying about something like that. But now that we’re at this point I can see they will be annoyed at any perceived “thunder-stealing” in the run-up to the day too and I just don’t want to be putting our lives on hold for people that we don’t even like and aren’t close to (although I don’t want to cause any rifts in DP’s family, but I feel they would be the ones causing the rift IYSWIM?) We of course wouldn’t do it the week before - probably a couple of months before.
We don’t have any mutual friends and their family is quite small so the number of people who would be interested in both relationships is about 10. We would obviously NOT be spending their wedding talking loudly about our own engagement - all our focus would be on them and their day. We will probably see them twice between now and their wedding day and I’d be happy to focus our conversation on their day both times. I’m not interested in attention, I just want to start planning with DP!
The main reason I’m annoyed is that DP and I aren’t exactly spring chickens anymore - we are the last to get married in both of our friendship groups and we want to have DC eventually but want to be married first - if we don’t start planning our wedding until October then lots of places and providers will be booked up for next summer already, so we’ll either have less choice or have to delay our wedding until next autumn which I don’t really want to do! Also knowing them they will probably be annoyed if we announce before they are back from their honeymoon so that’s another couple of weeks’ delay!
AIBU?